两种肺复张法对重度烟雾吸入性损伤犬相关指标的影响

Effects of two kinds of lung recruitment maneuvers on the correlated indexes of dogs with severe smoke inhalation injury

目的观察比较控制性肺膨胀（SI）和呼气末正压（PEEP）递增法（IP）这2种肿复张方法对重度烟雾吸入性损伤犬氧合、呼吸以及血流动力学的影响，方法将12只常规机械通气后全制成重度烟雾吸入性损伤模型，按随机数7表法分为SI组和IP组，每组6只-SI组全改行持续气道正压通气，吸气压力25cmH2O（1cmH2O=0．098 kPa），持续20s；IP组逐步升高PEEP水平，每隔5min增加5cmH2O直至25cmH2O，后每隔5min降低5cmH2O直至2～3cmH2O随后2组全均改行分组前通气模式，持续通气8h。于伤前、致伤后即刻及分组后治疗2、4、6、8h测定2组犬血分析指标pH值、PaO2、PaCO2并计算氧合指数（01），记录呼吸力学参数吸气峰压（PIP）、平均气道压、动态肺应性以及血流动力学参数心率、平均动脉压（MAP）、肺动脉压（PAP）、心排血压（CO）。对数据行重复测量差分析和LSD-t检验，结果（1）治疗6、8h，SI组犬pH值显著低于IP组（t值分别为2．431、2．261，P值均小于0．05）；PaO2分别为（87±24）、（78±14）mmHg（1mmHg=0．133kPa），均明显低于IP组的（114±18）、（111±17）mmHg（t值分别为2．249、3．671，P＜0．05或P＜0．01）；01显著高于IP组（t值分别为2．363、5．010，P＜0．05或P＜0．01）。组间及组内PaCO2水平比较，均未见明显差异（t值为0．119～1．042，P值均大于0．05）。与组内致伤后即刻比较，2组犬各治疗时相点pH值均显著降低（IP组治疗6、8h除外，t值为2．292～3．222，P＜0．05或P＜0．01），PaO2均显著升高（t值为4．443～6．315，P＜0．05或P＜0．01），明显著降低（t值为2．773～9．789，P＜0．05或P＜0．01）。（2）2组犬各时相点PIP水平接近（t值为0．399～1．167，P值均大于0．05）。SI组治疗4、8h时平均气道压显著高于IP组（t值分别为1．926、1．190，P值均小于0．05）；治疗4、6、8h时动态肺顺应性分别为（9．5±1．9）、（12．8±2．1）、（13．1±1．8）ml／cmH2O，显著低于IP组的（11．6±1．2）、（15．4±1．8）、（14．9±0．8）ml／cmH2O（t值分别为2．289、2．303、2．238，P值均小于0．05）与组内致伤后即刻比较，2组犬各治疗时相点PIP、平均气道压均显著下降（t值为2．271～7．436，P＜0．05或P＜0．01），治疗6、8h时动态肺顺应性显著升高（t值为2．207～4．195，P＜0．05或P＜0．01）。（3）2组犬各时相点心率、MAP、PAP水平接近（t值为0．001～1．170，P值均大于0．05）；IP组治疗4、6、8h时CO分别为（0．6±0．3）、（0．6±0．4）、（0．5±0．7）L／min，显著低于SI组的（1．5±0．7）、（1．8±1．1）、（1．6±0．9）L／min（t值分别为3．028、2．511、2．363。P值均小于0．05）。与组内致伤后即刻比较，IP组犬治疗4、6、8h CO显著下降（t值分别为2．363、2．302、2．254,P值均小于0.05）结论2种肺复张方法均能有效改善重度烟雾吸入性损伤犬氧合及肺顺应性，IP改善肺顺应性效果，SI对主要血流动力学参数影响较小。

Objective To observe and compare the effects of two kinds of lung recruitment maneuvers,namely sustained inflation （SI） and incremental positive end-expiratory pressure （PEEP） （IP） on oxygenation,respiratory mechanics,and hemodynamics of dogs with severe smoke inhalation injury.Methods After being treated with conventional mechanical ventilation,12 dogs were inflicted with severe smoke inhalation injury.They were divided into group SI and group IP according to the random number table,with 6 dogs in each group.Dogs in group SI were subjected to continuous positive airway pressure ventilation,with inspiratory pressure of 25 cmH2O （1 cmH2O =0.098 kPa）,and it was sustained for 20 s.PEEP level in group IP was gradually increased by 5 cmH2O every 5 min up to 25 cmH2O,and then it was decreased by 5 cmH2O every 5 min until reaching 2-3 cmH2O.Then the previous ventilation mode was resumed in both groups for 8 hours.Blood gas analysis （pH value,PaO2,and PaCO2）,oxygenation index （OI）,respiratory mechanics parameters [peak inspiratory pressure （PIP）,mean airway pressure,and dynamic lung compliance],and hemodynamic parameters [heart rate,mean arterial pressure （MAP）,pulmonary arterial pressure （PAP）,and cardiac output （CO）] were recorded or calculated before injury,immediately after injury,and at post ventilation hour （PVH） 2,4,6,8.Data were processed with analysis of variance of repeated measurement and LSD-t test.Results （1） At PVH 6 and 8,pH values of dogs in group SI were significantly lower than those in group IP （with t values respectively 2.431 and 2.261,P values below0.05）; PaO2 levels in group SI [（87 ±24）,（78 ± 14） mmHg,1 mmHg=0.133 kPa] were lower than those in group IP [（114 ± 18）,（111 ± 17） mmHg,with t values respectively 2.249 and 3.671,P 〈 0.05 or P 〈 0.01] ; OI values in group SI were significantly higher than those in group IP （with t values respectively 2.363 and 5.010,P 〈 0.05 or P 〈 0.01）.No significant differences were observed in PaCO2 level within each group or between the two groups （with t values from 0.119 to 1.042,P values above 0.05）.Compared with those observed immediately after injury,the pH values were significantly lowered （except for dogs in group IP at PVH 6 and 8,with t values from 2.292 to 3.222,P 〈0.05 or P 〈0.01）,PaO2 levels were significantly elevated （with t values from 4.443 to 6.315,P 〈 0.05 or P 〈 0.01）,and OI values were significantly lowered （with t values from 2.773 to 9.789,P 〈 0.05 or P 〈 0.01） in both groups at all the treatment time points.（2） The PIP level at each time point showed no significant differences between two groups （with t values from 0.399 to 1.167,P values above 0.05）.At PVH 4 and 8,the mean airway pressure values of dogs in group SI were significantly higher than those in group IP （with t values respectively 1.926 and 1.190,P values below 0.05）.At PVH 4,6,and 8,the dynamic lung compliance levels of dogs in group SI [（9.5 ± 1.9）,（12.8 ±2.1）,（13.1 ±1.8） mL/cmH2O] were significantly lower than those in group IP [（11.6 ± 1.2）,（15.4 ± 1.8）,（14.9 ±0.8） mL/cmH2O],with t values respectively 2.289,2.303,2.238,P values below 0.05.Compared with those observed immediately after injury,PIP and the mean airway pressure values of dogs in two groups were significantly lowered at each treatment time point （with t values from 2.271 to 7.436,P 〈 0.05 or P 〈 0.01） ; the dynamic lung compliance levels were significantly elevated in both groups at PVH 6 and 8 （with t values from 2.207 to 4.195,P 〈0.05 orP 〈0.01）.（3） Heart rate,MAP,and PAP levels at each time point between two groups showed no significant differences （with t values from 0.001 to 1.170,P values above 0.05）.At PVH 4,6,and 8,CO levels in group IP [（0.6 ±0.3）,（0.6±0.4）,（0.5 ±0.7） L/min] were significantly lower than those in group SI [（1.5 ±0.7）,（1.8 ± 1.1）,（1.6 ±0.9） L/min],witht values respectively 3.028,2.511,2.363,P values below 0.05.Compared with that observed immediately after injury,CO level in group IP was significantly lowered at PVH 4,6,or 8 （with t values respectively 2.363,2.302,2.254,P values below 0.05）.Conclusions Both lung recruitment maneuvers can effectively improve oxygenation and lung compliance of dogs with severe smoke inhalation injury.IP is more effective in improving lung compliance,while SI shows less impact on the hemodynamic parameters.